1. Field of the Invention
The present invention relates to an electrode for a battery and a method for manufacturing thereof and, more particularly, to a silicon electrode for a battery, which comprises periodically arrayed nanostructures that contribute to the improvement of battery life and capacity, and a method for manufacturing thereof, which can simply and easily form a nanopattern with nanostructures on a silicon thin film using laser interference lithography (LIL) and dry etching.
2. Description of the Related Art
As the use of portable electronic devices has increased due to the development of science and technology, the demand for secondary batteries which can be used through repeated charging and discharging has increased rapidly. Among them, a lithium secondary battery has attracted much attention due to its high voltage and high energy density.
The lithium secondary battery comprises a cathode, an anode, an electrolyte, a separator, an exterior material, etc. The cathode is configured in such a manner that a mixture of a cathode active material, a conductive material, a binder, etc. is applied to a current collector. Lithium-transition metal composite oxides such as LiCoO2, etc. are mainly used as cathode active materials. Carbonaceous materials such as carbon, graphite, etc. which have a relatively low potential, are typically used as anode active materials. However, the carbonaceous materials have a theoretical capacity of about 372 mAh g−1, and thus the development of new anode active materials is required to increase the capacity of the battery.
Meanwhile, silicon is attracting increasing attention as a next-generation electrode material which can replace the carbonaceous materials and can be used as an anode of a Li-ion secondary battery. The silicon has advantages of high theoretical capacity that is about 10 times higher than the carbonaceous materials (4200 mAh g-1), relatively low working potential (˜0.5 V vs. Li/Li+), and very high energy storage density. However, despite these advantages, an electrode using silicon has the problem of large volume change of approximately 400% occurring during Li-Si alloying/dealloying. The electrode using silicon undergoes significant structural stress due to repeated volume changes through continuous charge/discharge and thus is mechanically very unstable. Therefore, cracks occur or part of the electrode is detached from the current collector. Moreover, the cracked portion reduces the electrical contact between particles, which increases the contact resistance. In the part of the electrode detached from the current collector, lithium ions are isolated and do not participate in the electrode reaction any longer, thereby reducing the cycle performance.
Recently, extensive research aimed at synthesizing silicon in the form of nanowires or nanotubes has continued to progress to solve the above problems [Chan, C. K.; Peng, H.; Liu, G.; McIlwarth, K.; Zhang, X. F.; Huggins, R. A.; Cui, Y. Nat. Nanotechnol. 2008, 3, 31., Song, T.; Xia, J.; Lee, J.-H.; Lee, D. H.; Kwon, M.-S.; Choi, J.-M.; Wu, J. Doo, S. K.; Chang, H.; Park, W. I.; Zang, D. S.; Kim, H.; Huang, Y.; Hwang, K.-C.; Rogers, J. A.; Paik, U. Nano Lett. 2010, 10, 1710. etc.]. However, most of the silicon nanowires or nanotubes are grown or deposited to have a non-periodic array, and thus there are structural limitations. Moreover, the silicon nanowires or nanotubes are prepared by various bottom-up methods in which they are formed by growth from a thin film, and thus there are disadvantages to the process such as the complexity of the manufacturing process, an increase in the manufacturing process, etc.